Q 12-03-027NEETJEE MainMedium
A wire of resistance $R$ is stretched until its radius becomes half. Its new resistance is
Answer: (D) $16R$
Halving the radius makes $A$ one-fourth; constant volume makes $L$ four times. $R' = R \times 4 \times 4 = 16R$.
Solution by Sreeraj P, M.Sc Physics